HR: 13:55h
AN: P23E-02    [Abstracts]
TI: SPICAV: A suite of Three Spectometers to Study the Global Structure and Composition of the Venus Atmosphere
AU: Korablev, O
EM: korablev@aerov.jussieu.fr
AF: Space Research Institute (IKI), 84/32 Profsoyuznaya, Moscow, 117810 Russian Federation
AU: * Bertaux, J
EM: bertaux@aerov.jussieu.fr
AF: Service d'Aeronomie du CNRS/IPSL, BP3, Verrieres-le-buisson, 91371 France
AU: Nevejans, D
EM:
AF: Belgian Institute for Space Aeronomy, 3 av. Circulaire, Brussels, B-1180 Belgium
AU: Villard, E
EM:
AF: Service d'Aeronomie du CNRS/IPSL, BP3, Verrieres-le-buisson, 91371 France
AU: Dubois, J
EM:
AF: Service d'Aeronomie du CNRS/IPSL, BP3, Verrieres-le-buisson, 91371 France
AU: Neefs, E
EM:
AF: Belgian Institute for Space Aeronomy, 3 av. Circulaire, Brussels, B-1180 Belgium
AB: SPICAV (SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Venus) is a suite of three spectrometers in the UV and IR range with a total mass of 12.3 kg to be flown on Venus Express orbiter, dedicated to the study of the atmosphere of Venus from ground level to the outermost hydrogen corona at more than 40,000 km. It is derived from the SPICAM instrument already flying on board Mars Express (MEX), with the addition of a new IR high resolution spectrometer, SOIR, working in the solar occultation mode. A UV spectrometer (118 - 320 nm, resolution 1.5 nm) is identical to the MEX version. In nadir orientation, SPICAV UV will analyze the albedo spectrum (solar light scattered back from the clouds) to retrieve SO2, and the distribution of the UV-blue absorber (of still unknown origin) on the day side . On the night side, gamma and delta bands of NO will be studied, as well as emissions produced by electron precipitations. In the stellar occultation mode the UV sensor will measure the vertical profiles of CO2, temperature, SO2, SO, clouds and aerosols. The density/temperature profiles obtained with SPICAV will constrain and aid in the development of dynamical atmospheric models, from cloud top (~60 km) to 160 km in the atmosphere. This is essential for future missions that would rely on aerocapture and aerobraking. UV observations of the upper atmosphere will allow studies of the ionosphere through the emissions of CO, CO+, and CO2+, and its direct interaction with the solar wind. It will study the H corona, with its two different scale height: it will allow a better understanding of escape mechanisms and estimates of their magnitude, crucial for insight into the long-term evolution of the atmosphere. The SPICAV VIS-IR sensor (0.7-1.7 æm, resolution 0.5-1.2 nm) employs a pioneering technology: acousto-optical tunable filter (AOTF). On the night side, it will study the thermal emission peeping through the clouds, complementing the observations of both VIIRTIS and Planetary Fourier Spectrometer (PFS). In solar occultation mode this channel permits to study the vertical structure of H2O, CO2, and aerosols. The SOIR spectrometer is a new Solar Occultation IR spectrometer in the range λ=2.2-4.3 æm, with a spectral resolution >15,000, the highest on board Venus Express (VEX). This new concept includes a combination of an echelle grating and an AOTF crystal to sort out one order at a time. The main objective is to measure HDO and H2O in solar occultation, in order to characterize the escape of D atoms from the upper atmosphere and give more insight about the evolution of water on Venus. It will also study isotopes of CO2, minor species, and provides a sensitive search for new species in the upper atmosphere of Venus. It will be attempted to measure also the night side emission, which would allow a sensitive measurement of HDO in the lower atmosphere, to be compared to the ratio in the upper atmosphere, and possibly discover new minor atmospheric constituents.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0310 Airglow and aurora
DE: 0325 Evolution of the atmosphere (1610, 8125)
DE: 0343 Planetary atmospheres (5210, 5405, 5704)
SC: Planetary Sciences [P]
MN: Fall Meeting 2005